1. Field of the Invention
The present invention relates to a stripping agent composition for photoresist layer stripping used in a method for manufacturing a semiconductor integrated circuit, and a photoresist stripping method using the stripping agent composition.
2. Background Art
Semiconductor integrated circuits are manufactured by coating a photoresist on an inorganic base, exposing the photoresist to light, developing the exposed photoresist to form a pattern, then providing the patterned photoresist as a mask, etching the inorganic base in its non-mask area to form a fine circuit using the mask, and stripping the photoresist film (mask) from the inorganic base. The photoresist film is stripped with a stripping agent or by ashing the photoresist film and then removing the resist residue remaining unremoved from the inorganic base with the stripping agent.
A stripping agent comprising an ethylene oxide adduct of an alkanolamine or a polyalkylene polyamine, a sulfone compound, and a stripping agent comprising a glycol monoalkyl ether (Japanese Patent Publication No. 12455/1994) or a stripping agent comprising dimethyl sulfoxide as a main component and a diethylene glycol monoalkyl ether and a nitrogen-containing organic hydroxy compound (Japanese Patent No. 2578821) has hitherto been used as the stripping agent for the removal of the photoresist film or for the removal of photoresist residue and the like.
In the stripping agent, however, the amine dissociates with moisture absorbed in use, and, as a result, the stripping agent is rendered alkaline. The alkaline stripping agent is highly corrosive against aluminum, copper or the like which is a wiring material. When the base is rinsed with water after stripping the resist, the stripping agent remaining on the base is miscible with water to render the stripping agent strongly alkaline. Accordingly, aluminum, copper and the like which are wiring materials are disadvantageously corroded. In circuit boards in recent years, due to ultrafine interconnection, the dimensional accuracy requirement is strict, and, thus, the corrosion of the wiring material is unfavorable. Accordingly, when the alkaline stripping agent is used, in order to completely remove the remaining stripping agent, rinsing with an organic solvent such as alcohol is necessary, leading to a problem such as complication of the process.
In addition, water-free organic amine stripping agents are disclosed (Japanese Patent Publication No. 82238/1995 and Japanese Patent No. 3095296). However, these organic amine stripping agents are sometimes poor in the power of stripping the resist film after etching or stripping the resist residue after ashing. Further, in some cases, dry etching renders the surface of the resist film hard. In the organic amine stripping agents, however, the resultant hard resist film cannot be completely removed without difficulties. Furthermore, the composition of the resist residue produced by etching or plasma ashing is also complicated. In the organic amine stripping agents, the removal of the resist film or the resist residue is unsatisfactory. Further, when dry etching is adopted as the etching, due to mutual action among the gas, resist, and various inorganic materials used in the dry etching, a side-wall polymer which is a kind of resist residue is produced. Also for the side-wall polymer, the conventional organic amine stripping agent has poor stripping power.
On the other hand, water-containing alkanolamine stripping agents are disclosed (Japanese Patent Publication Nos. 69618/1995 and 69619/1995 and Japanese Patent No. 3048207). Even the water-containing alkanolamine stripping agents, however, do not offer a satisfactory effect in removing the resist film or removing the resist residue.
Accordingly, a photoresist stripping agent composition that can easily strip the above photoresist residue and the like at a low temperature in a short time, does not corrode the wiring material at all, and can be rinsed with water alone has been desired. Regarding the above stripping agent, for example, Japanese Patent Laid-Open No. 190205/1996 proposes a photoresist stripping agent composition comprising 5 to 50% of an alkanolamine compound, an alkoxyalkylamine compound, or an alkoxyalkanolamine compound, 1 to 30% of a glycol monoalkyl ether, and 0.5 to 15% of a saccharide or a sugar alcohol with the balance consisting of water. Further, Japanese Patent Laid-Open No. 202051/1996 proposes a photoresist stripping agent composition comprising 5 to 50% of an alkanolamine compound, alkoxyalkylamine compound or an alkoxyalkanolamine compound, 1 to 30% of an acid amide, and 0.5 to 15% of a saccharide or a sugar alcohol with the balance consisting of water. These stripping agents, however, have an unsatisfactory stripping speed. Resist stripping agents comprising an amine containing an n-hydroxymethyl group (Japanese Patent No. 4224651) and stripping agents comprising a combination of an amine compound, a specific aldehyde compound, and an aromatic hydroxy compound (Japanese Patent No. 4320865) are also proposed. These resist stripping agents, however, are poor in safety and stability of compounds.